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  <title>Graph2d | Streaming data</title>

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    body, html, select {
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<h2>Graph2d | Streaming data</h2>
<p style="max-width: 700px;">
  This example demonstrates how to apply streaming data input to the Graph2d. The example shows two different ways to let the window move along with the new data, and there are more strategies for that. Note also that it is possible to disable moving and/or zooming the graph by setting options <code>moveable</code> and <code>zoomable</code> false.
</p>

<p>
  <label for="strategy">Strategy:</label>
  <select id="strategy">
    <option value="continuous" selected>Continuous (CPU intensive)</option>
    <option value="discrete">Discrete</option>
    <option value="static">Static</option>
  </select>
</p>

<div id="visualization"></div>

<script type="text/javascript">
  var DELAY = 1000; // delay in ms to add new data points

  var strategy = document.getElementById('strategy');

  // create a graph2d with an (currently empty) dataset
  var container = document.getElementById('visualization');
  var dataset = new vis.DataSet();

  var options = {
    start: vis.moment().add(-30, 'seconds'), // changed so its faster
    end: vis.moment(),
    dataAxis: {
      left: {
        range: {
          min:-10, max: 10
        }
      }
    },
    drawPoints: {
      style: 'circle' // square, circle
    },
    shaded: {
      orientation: 'bottom' // top, bottom
    }
  };
  var graph2d = new vis.Graph2d(container, dataset, options);

  // a function to generate data points
  function y(x) {
    return (Math.sin(x / 2) + Math.cos(x / 4)) * 5;
  }

  function renderStep() {
    // move the window (you can think of different strategies).
    var now = vis.moment();
    var range = graph2d.getWindow();
    var interval = range.end - range.start;
    switch (strategy.value) {
      case 'continuous':
        // continuously move the window
        graph2d.setWindow(now - interval, now, {animation: false});
        requestAnimationFrame(renderStep);
        break;

      case 'discrete':
        graph2d.setWindow(now - interval, now, {animation: false});
        setTimeout(renderStep, DELAY);
        break;

      default: // 'static'
        // move the window 90% to the left when now is larger than the end of the window
        if (now > range.end) {
          graph2d.setWindow(now - 0.1 * interval, now + 0.9 * interval);
        }
        setTimeout(renderStep, DELAY);
        break;
    }
  }
  renderStep();

  /**
   * Add a new datapoint to the graph
   */
  function addDataPoint() {
    // add a new data point to the dataset
    var now = vis.moment();
    dataset.add({
      x: now,
      y: y(now / 1000)
    });

    // remove all data points which are no longer visible
    var range = graph2d.getWindow();
    var interval = range.end - range.start;
    var oldIds = dataset.getIds({
      filter: function (item) {
        return item.x < range.start - interval;
      }
    });
    dataset.remove(oldIds);

    setTimeout(addDataPoint, DELAY);
  }
  addDataPoint();
</script>
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